Borderlands 2 Skill Calculator

Skills are usually various class-specific attributes that modify a character’s abilities. By choosing a particular combination of skill-set, a player is able to customize their character, thus making that character more effective for certain play styles. 

Beyond the Action Skill, access to the different character skills or skill-set is regulated by a tree-like structure. Here, each class has 3 distinct skill trees. 

Each of these diverse trees comprises 7 different skills that are arranged into 4 successive tiers. So, the first 3 tiers of a tree contain two skills each, while the last tier only contains a single yet powerful skill.

In the beginning, the character will have access only to skills that are present in the first tier of each tree which is unlocked by the Action Skill. 

For every five skill points input in a particular tree, another tier in that tree unlocks itself, thus allowing skill points to be invested in new skills altogether. 

Hence, skill points may be invested in any set or combination of the skills in the available tiers: maxing a single skill by eventually investing five skill points in it is also possible, but not necessarily required to be advanced.  

Similarly, characters need not necessarily be dedicated to a single skill tree, but may distribute skill points between trees as and when the player sees fit.